Reflective surfaces can brighten Metro stations

Many complain that Metro's subway stations aren't bright enough, but they're surprisingly not that dim compared to other systems. Better surfaces can ensure that the limited lighting available is used more effectively without altering Metro stations' iconic appearance.

Which of these stations do you think is better lit? This one in Vancouver:

Believe it or not, Vancouver's transit agency specifies platform lighting 60% dimmer than WMATA's: their standard is 4 foot-candles, versus 10 foot-candles for WMATA. I usually read when I'm aboard transit, and whereas I have to seek out light on Metro subway platforms, I've never thought twice about the brightness on TransLink platforms. (Admittedly, I've spent much less time on the latter, partly due to the automated system's startlingly low headways).

It's not how much lighting, but how to use lighting

The difference is that TransLink also specifies high-reflectance, light-colored walls and floors, which direct light into occupied areas so that they feel much brighter. With "passive illumination," it's not just how much light is used, but also what the space does with that light.

Seemingly minor increases in reflectance for surfaces like walls and ceilings, particularly for indirect lighting scenarios, proportionately increase the brightness one can achieve with a given amount of light.

By comparison, much about the classic Metro station design thwarts attempts at improving lighting, and in fact intentionally so. Our standards of brightness have increased, partly because illumination has become so cheap.

Yet the stations' dark material palette, which includes unpainted concrete walls and ceilings, burgundy tiles, chocolate brown panels, even the bronze railings, absorbs what little light new fixtures add. These materials also attract dirt, which further darkens the stations over time.

However, using more reflective materials can also improve station lighting. That's the gist behind Metro's proposed changes to the Bethesda station, like replacing brown metal panels and concrete walls with brushed metal and clear glass. These changes will definitely help, but a more comprehensive approach could look at other changes that can improve lighting without dramatically impacting the stations' canonical appearance.

Laying a clear polymer coat on existing concrete surfaces could increase reflectance, reduce porosity and repel dirt, making cleaning easier. Painting the station vaults has proven controversial throughout Metro's history: Zachary Schrag's book The Great Society Subway points to a 1968 disagreement between the designers Harry Weese and William Lam as to whether to paint the vaults, and notes Weese's "commitment to 'pure structure in plain concrete' " in criticizing a 1990s decision by WMATA to paint some vaults.

But advances in construction materials now mean that light reflectance surprisingly has less to do with color as one might expect. A darker color with a slight gloss reflects more than a brighter color with a dull finish.

Today, much of the lighting in underground stations come from fluorescent tubes recessed within wells that are out of sight, beyond the platform edge or between the tracks. Since these surfaces are so close to the light sources, small changes here will result in big changes throughout.

Cleaning and brightening surfaces within these wells will result in more light reflected upwards into the station, as well as adding reflectors below the tubes to "catch" light that's currently pointing downwards, moving wire conduits so that they're below lights instead of blocking them, and replacing bronze-colored diffusers above the between-track tubes with clear plastic diffusers.

The stations' coffered ceilings have acoustic panels in them, which can be made brighter. These panels cover a surprising amount of the vaults' surface area, but because they're literally in the concrete's shadows, we don't tend to notice them very much.

These, too, accumulate dirt and dust over time, and over time they could be replaced by more reflective panels. The new Rosslyn entrance has highly reflective panels embedded within its coffers, which I didn't even notice the first few times I walked through it.

Similarly, WMATA could replace the drop-ceiling tiles underneath station mezzanines with tiles that reflect more light. Given the low ceiling heights in these spaces and the fact that they're largely hidden from view, a more ambitious upgrade could replace these with ceiling tiles with embedded LED lamps, reducing both shadows and glare in these areas while improving efficiency over the existing can lights. LED ceiling tiles might sound gaudy, but look no different than the fluorescent panels embedded in most office drop ceilings.

Attention to these details can ensure that the maximum possible amount of light is available within Metro's subway stations, improving energy efficiency, safety, comfort, and accessibility without altering their iconic appearance.

Payton Chung, LEED AP ND, CNUa, sees the promises and perils of planning every day as a resident of Southwest Washington. He first addressed a city council about smart growth in 1996, accidentally authored Chicago's inclusionary housing law, blogs at west north, and contributes to Streetsblog.

Comments

The other night I was on the Blue/Orange lower level platform at Metro Center and was pleasantly surprised that they've (FINALLY) finished the new ceiling tiles down there. They don't really blend very well with the architectural lines of Metro, but they're bright white and provide A LOT of pleasant reflective light where it was previously very dark.

The new ceiling tiles at Metro Center (lower platform) extend a foot below where they were, which just looks odd. I can't figure out why the ceiling was lowered in some stations and not others as the tiles were replaced. The new tiles do reflect light better.

The strange-looking Bethesda Station makeover is a mistake. Hiring no-name designers to redesign the work of a great architect (in Google Sketchup no less) is never a good move. There are other, cheaper alternatives to making the stations brighter. I honestly don't believe all the underground stations need that much more illumination. A modest increase should be sufficient to make most people happy.

Probably somewhere in the middle would be my preference. I don't necessarily need harsh ligh at 7am or 11pm. Using reflective materials and softer light sources is probably a good way to get more light without it becoming sterile feeling.

A darker color with a slight gloss reflects more than a brighter color with a dull finish.

Is this actually true? We were taught otherwise by our environmental design teacher.

Why should metro's lighting be as nauseatingly flat as an office building's? Metro would benefit from more careful placement of lighting, focusing attention to what is better lit. The escalators need lighting at the ground level. The platforms need more at waist height, where you hold a book.

For future stations, metro might want to look at precastglass fiber-reinforced concrete. It can be made more consistently white, reflective, water resistant, and thin than the poured-in-place that makes the Gallery Place station so dark, or the precast panels of the 4- and 6- piece stations like Tenleytown or Petworth.

I know this is an unpopular opinion, but I very much like the current level of lighting in most stations.

Most offices have way too much fluorescent lighting in them and many outdoor parts of our city suffer from light pollution in the name of security. Hell, even the newer Metro cars have harsh lighting in them (compare the lighting in a 6000 to that of a 1000). So for me at least, entering the softly lit underground stations provides a nice break and a has a calming, almost peaceful effect. We only spend a few minutes each day down there (if that) and it is, well, subterranean.

Yeah I agree with a lot of the comments above. I appreciate the small things and distinctions. I like the lights in the Dupont escalators. I think some subtle colored tile work that corresponds to the color(s) of the lines that go through the station could be really classy. Spot lighting rather than overwhelming illumination would be appreciated by many people I think.

Just as a general note, it can be very disingenuous to ask people to compare photos unless they're taken using the same settings.

That being said, these images *are* a relatively good example because they were taken with the same f-stop and at very similar ISOs and with similar exposures.

Believe it or not, the Gallery Place exposure was /longer/ than the Vancouver exposure (which should make the DC photo relatively brighter than it would be if taken with the same values as the Vancouver shot). But it's only a slight difference.

The Vancouver picture is at f/2.8, ISO 200, and is a 0.04 second exposure.

The great thing about increasing surface reflectance vs. increasing lighting is that it doesn't impact the station architecture, much less the indirect-lighting design that makes the station lighting so soft. So these strategies just won't result in harsh and overly bright lighting, and worries to that effect aren't warranted. Indeed, the one place where I recommend adding fixtures (mezzanine undersides) would have more evenly diffused lighting. Having one area on the platform bright enough for reading paper might defuse the complaints about stations being too dark.

Aaand... someone who commutes in off-peak hours can easily spend 20+ minutes a day on Metro platforms. A comfortable way to pass the time makes a huge difference. Of course, there are lots of things that can be improved about Metro, but that doesn't mean that small changes should be ignored. This line of reasoning is defeatist and simple-minded: we could all stand to eat more healthfully, but that hardly means that we shouldn't also clean the house. People, much less big organizations like WMATA, are capable of multi-tasking.

@Matt: Good catch; hadn't thought to dig into the EXIF info, but it did occur to me to not choose photos which were looking directly into the lights, as that would influence the cameras' auto-exposure.

@Neil: take a look at the light reflectance values (LRVs) for different shades of the same material, e.g., these composite exterior panels. Under the "mica," "metallic," and "natural metals" finishes, the lightest color reflect less light than the mid-range colors.

One significant problem in Metro stations is the number of bulbs that are out or lighting fixtures that don't work. I would be happier if that situation could be dealt with, but in the long run, I definitely prefer the seemingly brighter Vancouver stations.

It's silly to talk about big redesigns before we've seen what happens if metro got their act together and took simple steps like cleaning the walls at least once a decade and replacing light bulbs that burn out.

Great Article! I live at Stadium Armory which was recently repainted. During the painting process I think they used a primer first which was a very light grey and made the whole station feel way better. Unfortunately the came back over it with a darker grey.

The whole process took several weeks so you could see the bright color slowly getting eliminated, very depressing.

So basically this article demonstrates that Metro uses more lighting but still has darker stations than, e.g., Vancouver's system, confirming what we already know, that WMATA is as inefficient as they come.

Judiciary Sq does stand out...too bad it took so long for WMATA to realise this and is taking longer to bring other stations up to speed.

Sand Box John: Maybe that was sarcastic, but Dryvit and other artificial plasters like it are water and air resistant to the point that they've caused serious mold issues on buildings. Given the metro's big water issues, I feel like that could be catastrophic. I also think it never looks precise.

Payton: Sure, if you're talking about specular reflections adding to the diffuse reflectance, there can be some overlap of brightness. But the semi-gloss whites, yellows, and beiges are 2+ times brighter than the metallic finishes you mention. On the other hand, mirrorlike panels would useful for reflecting light to specific places where it can be the most useful.

I saw many of them long before the first train rolled into them. No amount of cleaning will make them look "clean and shiny". Their dirty appearance is the result of the unintended consequences of the way they were finished after the forms were striped. The precast stations are not nearly as bad as the cast in place stations.

@Neil Flanagan
I doubt that mold would be an issue as the temperature and humidity in the stations are out of the range most of the time that it would in reduce its growth. The HVAC equipment in the station in subway act as dehumidifier. I would hazard a guess the folks at Dryvit have reformulated their products with chemical additives to inhibit mold growth in the environments where you say they have had problems.

As to it imprecise appearance, that is the result of the skill of the installer.

Have you looked down the horizontal reveals between the coffers in most of the cast in place stations, those stations are poster children for imprecise concrete work. With some proper prep work those flaws could be remove before applying the Dryvit.

Terrible idea. The painted stations look horrible and will have to be repainted every few years to look "clean". What do we need more light for exactly? Are people stumbling around and falling onto the tracks? The lighting is calming and restful.

While adding these reflective surfaces, the acoustics need should be kept in mind. Most of the shiny surfaces are made of metal and they cannot diffuse sound due to which noisy metro environment would become even worse to bear when the new installation will be completed.
These are the lessons learnt from Church Acoustics over the past.

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